5.0L (1979-1995) MustangTechnical discussions on 5.0 Liter Mustangs within. This does not include the 5.0 from the 2011 Mustang GT. That information is in the 2005-1011 section.
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Electrical Problem

Long story short, finished with an engine tear down to find/fix a *tick*, plus add horsepower... new Comp XE276HR cam, lifters, pushrods, valve springs, timing chain, rockers (plus some miscellaneous accessories like plugs/wires)... new PowerMaster starter, new Yellow top Optima battery...

prior to this work (to fix the tick) the car would not restart once it was warm/hot. It would act like it had zero electrical power if I needed to restart (at this point it had an EXTREMELY cheap starter and cheap battery). Never had a problem while running tho...

moving on. Currently, now all the bugs are worked out (tho I'm still taking it up to Alternative Motorsports in Livonia in July for a dyno tune)... but it died 1 mile from my engine builders house tonight (with the lights on). But, We had test drove it numerous times over the prior weeks (with all these new parts - battery/starter) with no problems while driving. Some restarting problems.

So, at this point - common sense would say (since it died WHILE driving), alternator (or alternator related). But that was the literal first time it did that to me. the car has sat since 09... I've owned it since 05, and from 05-09 it always had the problem of not restarting once it was warm/hot

Any help? Thanks guys

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Just to clarify, you said the car had zero electrical power on a hot restart. Meaning no power for lights, radio, etc. I'd start with ignition switch. But you'd think heat wouldn't affect that, but you never know.

Now if you meant you had no electrical power as in spark during a hot start. Pull your TFI module and get it tested. Have them test it 3 times so it gets nice and hot.

When it died on the road, the interior lights were extremely dim. I realized I said "zero electrical power", but to clarify... dash lights were barely lit, and the fuel pump kick on is very very weak (not enough juice to even try to turn the motor over or click...).

The way its acted forever (won't restart when warm)... it would turn the motor over about once then click, and at that point the juice is basically gone.

Never mind what I said early, you have a bad ground somewhere. I'll almost guarantee it. Check and clean and I'll bet you find one loose or corroded. Start with the neg. battery cable ground on the block. And actually check both battery cables themselves.

That would be surprising, we pulled the motor, tore it down to the short block and I degreased and repainted everything

Ok, that's good, as long as you removed the paint where the neg. cable attaches to the block. Common sense I know, but the po of my car didn't know this. And my car ran perfect for 3 years until it started acting up like yours. I pulled that ground to find a thick coat of paint. Took it down to metal and all problems disappeared. A bad ground anywhere can do some really weird things.

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